<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>剩余宽高</title>
    <style>
        .box{
            width: 300px;
            height: 300px;
            border: 1px saddlebrown solid;
            display: flex;
            flex-direction: column;

        }
        .box div{
            width: 60px;
            height: 60px;
            border: 1px dotted rebeccapurple;
        }

        .box div:nth-child(2){
            /* 占满剩余控件 */
            flex: 2;
        }
        .box div:nth-child(1){
        }

        .box div:nth-child(3){
        }
        /* 全部设置安比例显示 某一项大设置大 根据横轴纵轴 一样的值平分*/

    </style>

</head>
<body>
    
    <div class="box">
        <div></div>
        <div></div>
        <div></div>

    </div>
</body>
</html>